SANTA CLARA, Calif. -- In a move that flew under the radar late last week, the San Francisco 49ers signed nickel cornerback K'Waun Williams to a three-year contract extension that will keep him with the team through 2020.

Taken by itself, it wasn't a surprising move given Williams' early-season performance and his history with defensive backs coach Jeff Hafley, which dates to Hafley's time at the University of Pittsburgh, where he recruited Williams and served as his position coach for a year. That duo reconnected with the Cleveland Browns in 2014 and 2015 with Hafley again working as Williams' position coach. Shanahan was also the Browns' offensive coordinator in 2014.

Williams' deal, which included a $3 million signing bonus, was the first long-term extension that new coach Kyle Shanahan and general manager John Lynch have given a player since they arrived in January. And in Williams' case, it came just three games into the season.

Now that we know the Niners are open to extending players they identify as wanting to keep, could more be in the offing or does Shanahan want to see bigger sample sizes from players who don't have the history Williams already had with Hafley and Shanahan?

"You have got to think what's the best for the whole team, for the individual, for the situation, you don't want to just jump into things quick," Shanahan said. "You do have some time on that stuff but we're looking at every person, we're aware of everyone who is in that situation and it's nice to have games and have time to do it, too."

Here's a look at some of the Niners' pending free agents (and someone who isn't) who could be next in line:

RB Carlos Hyde -- Remember the offseason when the Niners were openly praising draft prospect Leonard Fournette and some were speculating the team might even move on from Hyde and use the second pick on Fournette? Obviously, those things never played out and were probably never realistic to begin with. But if Shanahan and Lynch were taking the opportunity to light a spark under Hyde, it appears to have worked. After arriving to camp in the best shape of his career, Hyde is sixth in the NFL in rushing yards (321) and yards from scrimmage (409) and ninth in yards per carry (4.94). The Niners drafted Joe Williams and are believers in undrafted rookie Matt Breida but Hyde has clearly proved to be the best back on the roster. The question is whether a Shanahan-coached team is willing to invest a sizable amount in a running back? Hyde's price tag probably isn't overwhelming at this point, but if he can stay healthy (he's playing through an oblique injury right now and has missed time in previous seasons) and continue to produce, the 49ers will have to consider keeping him around. The Niners are rebuilding and creating more needs on the roster isn't the ideal approach, but it's also fair to expect San Francisco to want to see more from Hyde before committing to him, even if it means an increase in price.

S Eric Reid -- Reid looked to be a natural fit for the strong safety spot in new coordinator Robert Saleh's defense from day one. In fact, Reid looked more comfortable playing his new role in the preseason and the first game and a half than he had at any point in his career. He is also one of the team's leaders and a bedrock in the locker room. Alas, one of the primary questions the 49ers must answer is whether Reid can stay healthy enough to justify what will probably be a fairly expensive price. After missing only one game in his first three seasons, Reid missed six last year and has already missed two this season with more expected because of a knee injury. The Niners have some intriguing young safeties on the roster and might consider going with a younger, cheaper option. Like Hyde, Reid probably still has some proving to do when he returns from his sprained knee before the 49ers are willing to invest in him for the future.

C Daniel Kilgore, DE Tank Carradine, C Dontae Johnson, G Brandon Fusco -- There are a few others set for free agency after the season but these are the remaining starters who could hit the market. From this group, Kilgore would seem to be the most likely to be brought back, though he, too, must prove capable of staying healthy for an entire season. Upgrades at guard are still needed, so it's unlikely there will be a rush to re-sign Fusco. As for Carradine and Johnson, the Niners have already seemingly invested in their replacements. Rookie Solomon Thomas is starting for Carradine now after Carradine landed on injured reserve last week. Thomas is probably not going to give that starting job back though Carradine was playing pretty well before he got hurt and might be a nice piece to retain as part of a rotation. Johnson is starting opposite Rashard Robinson but the 49ers need to bolster their corner group in the offseason and spent a third-round pick on Ahkello Witherspoon, a player the Niners hope can develop into a starter.

OT Trent Brown -- Unlike the others listed here, Brown is not set to become a free agent until after the 2018 season. But, given how well he's developed and performed, it's not out of the realm of possibility that the Niners will attempt to lock him up this offseason when Brown becomes eligible for an extension. Through four games, Pro Football Focus rates Brown as the fourth-best tackle overall with the second-best pass blocking efficiency in the league. For the season, PFF has Brown down for one sack and two hurries allowed on 163 pass block snaps. The question with Brown has never been about his physical ability but whether he can be consistent. So far this season, he's done that and he could be in line for a massive payday in the near future.